News and commentary about the Great Frontiers

ISS007-E-10807 (21 July 2003) --- This view of Earth's horizon as the sunsets over the Pacific Ocean was taken by an Expedition 7 crewmember onboard the International Space Station (ISS). Anvil tops of thunderclouds are also visible. Credit: Earth Science and Remote Sensing Unit, NASA Johnson Space Center

Image Credit: ISS007-E-10807 (21 July 2003) – Earth Science and Remote Sensing Unit, NASA Johnson Space Center

Titan Ice Volcano?



Titan may harbor “ice volcanoes” and scientists have presented evidence for a likely candidate in the June 9 issue of Nature. Several images of the possible volcano were released to the Internet today by the Jet Propulsion Laboratory.

Ice volcanoes may explain the high level of methane present in Titan’s atmosphere. Methane generally breaks down over a relatively short period of time. Scientists presume some active process keeps high levels of methane in the atmosphere but are unsure which process is at work. Oceans or lakes of liquid methane have previously been proposed as an explanation but neither the Cassini space probe nor the Huygens lander has detected them. The alternative? Ice volcanoes, also known as cryovolcanoes.

Images taken by Cassini using various wavelengths of light suggest a circular surface feature northeast of the Huygens probe landing site. Various compositional layers superimposed on each other may indicate different flows from the volcano. However, any “lava” deposits would be made of methane-ice mixtures, perhaps with other hydrocarbons and ammonia mixed in. Internal heating may provide enough melting to allow eruption of this material onto the moon’s surface.

Future Cassini flybys should help clarify the situation. Cassini is currently focusing on Saturn’s rings, but will return to closer inspection of Saturn’s moons in July.

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